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author | 2022-07-21 14:03:29 +0100 | |
---|---|---|
committer | 2022-10-20 22:32:02 +0100 | |
commit | 23722fb46725da42b80bc55a91a9bac69e35188a (patch) | |
tree | 151b32d97106a5161fa88165db607ad184614b70 /drivers/hwtracing | |
parent | Linux 6.1-rc1 (diff) | |
download | linux-23722fb46725da42b80bc55a91a9bac69e35188a.tar.gz linux-23722fb46725da42b80bc55a91a9bac69e35188a.tar.bz2 linux-23722fb46725da42b80bc55a91a9bac69e35188a.zip |
coresight: Fix possible deadlock with lock dependency
With lockdeps enabled, we get the following warning:
======================================================
WARNING: possible circular locking dependency detected
------------------------------------------------------
kworker/u12:1/53 is trying to acquire lock:
ffff80000adce220 (coresight_mutex){+.+.}-{4:4}, at: coresight_set_assoc_ectdev_mutex+0x3c/0x5c
but task is already holding lock:
ffff80000add1f60 (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (ect_mutex){+.+.}-{4:4}:
__mutex_lock_common+0xd8/0xe60
mutex_lock_nested+0x44/0x50
cti_add_assoc_to_csdev+0x4c/0x184
coresight_register+0x2f0/0x314
tmc_probe+0x33c/0x414
-> #0 (coresight_mutex){+.+.}-{4:4}:
__lock_acquire+0x1a20/0x32d0
lock_acquire+0x160/0x308
__mutex_lock_common+0xd8/0xe60
mutex_lock_nested+0x44/0x50
coresight_set_assoc_ectdev_mutex+0x3c/0x5c
cti_update_conn_xrefs+0x6c/0xf8
cti_probe+0x33c/0x394
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(ect_mutex);
lock(coresight_mutex);
lock(ect_mutex);
lock(coresight_mutex);
*** DEADLOCK ***
4 locks held by kworker/u12:1/53:
#0: ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1fc/0x63c
#1: (deferred_probe_work){+.+.}-{0:0}, at: process_one_work+0x228/0x63c
#2: (&dev->mutex){....}-{4:4}, at: __device_attach+0x48/0x1a8
#3: (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394
To fix the same, call cti_add_assoc_to_csdev without the holding
coresight_mutex and confine the locking while setting the associated
ect / cti device using coresight_set_assoc_ectdev_mutex().
Fixes: 177af8285b59 ("coresight: cti: Enable CTI associated with devices")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220721130329.3787211-1-sudeep.holla@arm.com
Diffstat (limited to 'drivers/hwtracing')
-rw-r--r-- | drivers/hwtracing/coresight/coresight-core.c | 7 | ||||
-rw-r--r-- | drivers/hwtracing/coresight/coresight-cti-core.c | 5 |
2 files changed, 7 insertions, 5 deletions
diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index d5dbc67bacb4..f3068175ca9d 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1687,14 +1687,15 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) ret = coresight_fixup_device_conns(csdev); if (!ret) ret = coresight_fixup_orphan_conns(csdev); - if (!ret && cti_assoc_ops && cti_assoc_ops->add) - cti_assoc_ops->add(csdev); out_unlock: mutex_unlock(&coresight_mutex); /* Success */ - if (!ret) + if (!ret) { + if (cti_assoc_ops && cti_assoc_ops->add) + cti_assoc_ops->add(csdev); return csdev; + } /* Unregister the device if needed */ if (registered) { diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c index 8988b2ed2ea6..1be92342b5b9 100644 --- a/drivers/hwtracing/coresight/coresight-cti-core.c +++ b/drivers/hwtracing/coresight/coresight-cti-core.c @@ -541,7 +541,7 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name, /* * Search the cti list to add an associated CTI into the supplied CS device * This will set the association if CTI declared before the CS device. - * (called from coresight_register() with coresight_mutex locked). + * (called from coresight_register() without coresight_mutex locked). */ static void cti_add_assoc_to_csdev(struct coresight_device *csdev) { @@ -569,7 +569,8 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev) * if we found a matching csdev then update the ECT * association pointer for the device with this CTI. */ - csdev->ect_dev = ect_item->csdev; + coresight_set_assoc_ectdev_mutex(csdev->ect_dev, + ect_item->csdev); break; } } |